/* ========================================= */
/* 主体结构与基础样式 */
/* ========================================= */
:root {
    /* 主要颜色变量 - 蓝色系 */
    --primary-color: #0056b3; /* 核心蓝色 */
    --primary-dark: #004085;  /* 更深的蓝色，用于悬停 */
    --primary-light: #e0f2f7; /* 浅蓝色，用于背景或辅助色 */
    --accent-color: #4CAF50;  /* 强调色，如绿色或黄色，用于按钮高亮 */
    --text-color: #333;
    --light-text-color: #f8f8f8; /* 用于深色背景上的文字 */
    --border-color: #ddd;
    --bg-color-light: #f9f9f9;
    --bg-color-dark: #2c3e50; /* 深色背景，如页头页脚 */
}

body {
    font-family: 'Segoe UI', 'Microsoft YaHei', 'Helvetica Neue', Arial, sans-serif;
    margin: 0;
    padding: 0;
    background-color: var(--bg-color-light);
    color: var(--text-color);
    line-height: 1.6;
    scroll-behavior: smooth; /* 平滑滚动 */
}

.container {
    width: 90%;
    max-width: 1280px; /* 进一步增大内容区宽度 */
    margin: 0 auto;
    padding: 0 20px; /* 容器左右内边距 */
}

/* ========================================= */
/* 头部 Header */
/* ========================================= */
.main-header {
    background-color: var(--bg-color-dark);
    color: var(--light-text-color);
    padding: 15px 0;
    box-shadow: 0 3px 10px rgba(0,0,0,0.15);
    position: sticky; /* 粘性定位 */
    top: 0;
    z-index: 1000; /* 确保在最上层 */
}
.main-header .container {
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.header-left {
    display: flex;
    align-items: center;
}
.logo {
    display: flex;
    align-items: center;
    text-decoration: none;
    color: var(--light-text-color);
    font-size: 1.6em;
    font-weight: bold;
}
.logo img {
    height: 45px; /* Logo高度 */
    margin-right: 12px;
    border-radius: 5px;
}
.logo span {
    white-space: nowrap; /* 防止名称换行 */
}

/* 主导航栏 */
.main-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
    display: flex;
}
.main-nav ul li {
    margin-left: 35px;
    position: relative; /* 为下拉菜单定位 */
}
.main-nav ul li a {
    color: var(--light-text-color);
    text-decoration: none;
    font-weight: 500;
    padding: 10px 0;
    display: block;
    transition: color 0.3s ease, transform 0.2s ease;
    position: relative;
}
.main-nav ul li a::after {
    content: '';
    position: absolute;
    left: 50%; /* 从中间开始伸展 */
    transform: translateX(-50%);
    bottom: 0;
    width: 0;
    height: 3px;
    background-color: var(--primary-color);
    transition: width 0.3s ease;
}
.main-nav ul li a:hover::after,
.main-nav ul li a.active::after {
    width: 100%;
}
.main-nav ul li a:hover,
.main-nav ul li a.active {
    color: var(--primary-color);
}

/* 下拉菜单 */
.dropdown-content {
    display: none;
    position: absolute;
    background-color: #3a4b5c; /* 下拉菜单背景色 */
    min-width: 160px;
    box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
    z-index: 1;
    border-radius: 5px;
    overflow: hidden;
    top: 100%; /* 位于父元素下方 */
    left: 50%;
    transform: translateX(-50%);
    opacity: 0;
    visibility: hidden;
    transition: opacity 0.3s ease, visibility 0.3s ease, transform 0.3s ease;
}
.dropdown-content a {
    color: var(--light-text-color);
    padding: 12px 16px;
    text-decoration: none;
    display: block;
    text-align: left;
    white-space: nowrap;
    font-weight: normal;
}
.dropdown-content a:hover {
    background-color: var(--primary-dark);
    color: var(--light-text-color); /* 悬停时文字颜色不变 */
}
.dropdown:hover .dropdown-content {
    display: block;
    opacity: 1;
    visibility: visible;
    transform: translateX(-50%) translateY(5px); /* 略微下移效果 */
}

.header-right {
    display: flex;
    align-items: center;
}
.search-btn, .toggle-menu-btn {
    background: none;
    border: none;
    color: var(--light-text-color);
    font-size: 1.2em;
    cursor: pointer;
    margin-left: 20px;
    transition: color 0.3s ease;
}
.search-btn:hover, .toggle-menu-btn:hover {
    color: var(--primary-color);
}
.toggle-menu-btn {
    display: none; /* 默认隐藏，在移动端显示 */
}

/* 移动端菜单 */
.mobile-menu {
    display: none; /* 默认隐藏 */
    background-color: var(--primary-dark);
    color: var(--light-text-color);
    position: fixed;
    top: 0;
    right: -300px; /* 初始隐藏在右侧 */
    width: 280px;
    height: 100%;
    box-shadow: -5px 0 15px rgba(0,0,0,0.3);
    z-index: 999;
    transition: right 0.3s ease-out;
    padding-top: 80px; /* 留出头部空间 */
    box-sizing: border-box;
}
.mobile-menu.active {
    right: 0;
}
.mobile-menu ul {
    list-style: none;
    padding: 0;
    margin: 0;
}
.mobile-menu ul li a {
    display: block;
    padding: 15px 25px;
    color: var(--light-text-color);
    text-decoration: none;
    border-bottom: 1px solid rgba(255,255,255,0.1);
    transition: background-color 0.2s ease;
}
.mobile-menu ul li a:hover {
    background-color: rgba(255,255,255,0.1);
}


/* ========================================= */
/* 轮播图 Hero Section */
/* ========================================= */
.carousel-container {
    position: relative;
    width: 100%;
    max-width: 100%; /* 充满屏幕宽度 */
    margin: 0 auto 3em; /* 移除顶部外边距，下方留出空间 */
    overflow: hidden;
    height: 600px; /* 固定轮播图高度 */
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}
.carousel-slide {
    display: flex;
    height: 100%;
    transition: transform 0.6s cubic-bezier(0.25, 0.46, 0.45, 0.94); /* 更流畅的过渡 */
}
.carousel-item {
    min-width: 100%; /* 确保每个项占据100%宽度 */
    height: 100%;
    position: relative;
    display: flex;
    align-items: center;
    justify-content: center;
}
.carousel-item img {
    width: 100%;
    height: 100%;
    object-fit: cover; /* 裁剪图片以填充容器 */
    filter: brightness(0.7); /* 图片略微变暗，突出文字 */
}
.carousel-caption {
    position: absolute;
    color: white;
    text-align: center;
    max-width: 80%;
    z-index: 1;
    text-shadow: 0 2px 8px rgba(0,0,0,0.6);
    animation: fadeInSlideUp 0.8s ease-out forwards; /* 新增动画 */
}
.carousel-caption h2 {
    font-size: 3.8em;
    margin-bottom: 15px;
    letter-spacing: 1px;
}
.carousel-caption p {
    font-size: 1.5em;
    margin-bottom: 30px;
    max-width: 800px;
    margin-left: auto;
    margin-right: auto;
}
/* 轮播图切换按钮 */
.carousel-nav {
    position: absolute;
    top: 50%;
    width: 100%;
    display: flex;
    justify-content: space-between;
    transform: translateY(-50%);
    padding: 0 30px;
    box-sizing: border-box;
}
.nav-arrow {
    background-color: rgba(0,0,0,0.4);
    color: white;
    border: none;
    padding: 15px 20px;
    cursor: pointer;
    border-radius: 50%;
    font-size: 2em;
    transition: background-color 0.3s, transform 0.3s;
}
.nav-arrow:hover {
    background-color: rgba(0,0,0,0.7);
    transform: scale(1.1);
}
/* 轮播图圆点 */
.carousel-dots {
    position: absolute;
    bottom: 25px;
    left: 50%;
    transform: translateX(-50%);
    display: flex;
}
.carousel-dot {
    width: 14px;
    height: 14px;
    background-color: rgba(255,255,255,0.6);
    border-radius: 50%;
    margin: 0 8px;
    cursor: pointer;
    transition: background-color 0.3s ease, transform 0.2s ease;
    border: 2px solid transparent;
}
.carousel-dot.active {
    background-color: var(--primary-color);
    border-color: white;
    transform: scale(1.2);
}

/* ========================================= */
/* 通用标题和模块样式 */
/* ========================================= */
.section-padded {
    padding: 80px 0;
}
.section-heading {
    text-align: center;
    font-size: 3em;
    color: var(--primary-dark);
    margin-bottom: 1.5em;
    position: relative;
    padding-bottom: 15px;
}
.section-heading::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 50%;
    transform: translateX(-50%);
    width: 80px;
    height: 4px;
    background-color: var(--primary-color);
    border-radius: 2px;
}
.sub-heading { /* 用于二级页面内部标题 */
    font-size: 2.2em;
    color: var(--primary-dark);
    margin-bottom: 1em;
    padding-bottom: 10px;
    border-bottom: 2px solid var(--border-color);
    display: inline-block;
}

/* 通用按钮样式 */
.btn {
    display: inline-block;
    padding: 12px 30px;
    border-radius: 5px;
    text-decoration: none;
    font-weight: bold;
    font-size: 1.1em;
    transition: background-color 0.3s ease, transform 0.2s ease, box-shadow 0.3s ease;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}
.btn-primary {
    background-color: var(--primary-color);
    color: white;
    border: 2px solid var(--primary-color);
}
.btn-primary:hover {
    background-color: var(--primary-dark);
    border-color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}
.btn-secondary {
    background-color: var(--accent-color);
    color: white;
    border: 2px solid var(--accent-color);
}
.btn-secondary:hover {
    background-color: #3e8e41;
    border-color: #3e8e41;
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}
.btn-outline {
    background-color: transparent;
    color: var(--primary-color);
    border: 2px solid var(--primary-color);
}
.btn-outline:hover {
    background-color: var(--primary-color);
    color: white;
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}
.btn-white { /* 用于深色背景上的白色按钮 */
    background-color: white;
    color: var(--primary-color);
    border: 2px solid white;
}
.btn-white:hover {
    background-color: var(--primary-light);
    color: var(--primary-dark);
    transform: translateY(-2px);
    box-shadow: 0 4px 10px rgba(0,0,0,0.2);
}


/* ========================================= */
/* 核心价值 / 计数器动画 */
/* ========================================= */
.core-values {
    background-color: white;
}
.value-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 30px;
    margin-bottom: 60px;
}
.value-item {
    text-align: center;
    padding: 30px;
    background-color: var(--bg-color-light);
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
    border-bottom: 4px solid var(--primary-color); /* 底部强调线 */
}
.value-item:hover {
    transform: translateY(-8px);
    box-shadow: 0 8px 20px rgba(0,0,0,0.15);
}
.value-item i {
    font-size: 3.5em;
    color: var(--primary-color);
    margin-bottom: 20px;
}
.value-item h3 {
    font-size: 1.6em;
    color: var(--primary-dark);
    margin-top: 0;
    margin-bottom: 10px;
}
.value-item p {
    color: #666;
    font-size: 0.95em;
}

/* 计数器部分 */
.stats-counter-section {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    text-align: center;
    background-color: var(--primary-light); /* 浅蓝色背景 */
    padding: 40px;
    border-radius: 10px;
    box-shadow: inset 0 0 15px rgba(0,0,0,0.05);
}
.stat-item {
    color: var(--primary-dark);
}
.stat-item .counter {
    font-size: 3.5em;
    font-weight: bold;
    display: block;
    margin-bottom: 5px;
}
.stat-item p {
    font-size: 1.2em;
    color: #555;
    margin: 0;
}


/* ========================================= */
/* 视差滚动 Parallax Section */
/* ========================================= */
.parallax-section {
    background-attachment: fixed; /* 核心属性 */
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
    position: relative;
    min-height: 450px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: white;
    text-align: center;
    padding: 80px 0;
}
.parallax-section .overlay {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.5); /* 半透明遮罩 */
    z-index: 1;
}
.parallax-content {
    position: relative;
    z-index: 2;
    text-shadow: 0 2px 10px rgba(0,0,0,0.7);
}
.parallax-content h2 {
    font-size: 3.5em;
    margin-bottom: 20px;
}
.parallax-content p {
    font-size: 1.3em;
    max-width: 900px;
    margin: 0 auto 30px auto;
}


/* ========================================= */
/* 最新动态 / 新闻卡片 */
/* ========================================= */
.latest-news {
    background-color: white;
}
.news-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
    gap: 30px;
}
.news-card {
    background-color: var(--bg-color-light);
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 4px 15px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.news-card:hover {
    transform: translateY(-8px);
    box-shadow: 0 8px 25px rgba(0,0,0,0.15);
}
.news-thumbnail {
    width: 100%;
    height: 200px;
    background-size: cover;
    background-position: center;
    transition: transform 0.5s ease;
}
.news-card:hover .news-thumbnail {
    transform: scale(1.05);
}
.news-content {
    padding: 25px;
}
.news-content h4 {
    font-size: 1.4em;
    margin-top: 0;
    margin-bottom: 10px;
}
.news-content h4 a {
    color: var(--primary-dark);
    text-decoration: none;
    transition: color 0.3s ease;
}
.news-content h4 a:hover {
    color: var(--primary-color);
}
.news-meta {
    font-size: 0.9em;
    color: #777;
    margin-bottom: 15px;
}
.news-meta i {
    margin-right: 5px;
    color: var(--accent-color);
}
.news-content p {
    font-size: 0.95em;
    color: #555;
    margin-bottom: 15px;
}
.read-more-link {
    color: var(--primary-color);
    text-decoration: none;
    font-weight: bold;
    transition: color 0.3s ease;
}
.read-more-link:hover {
    color: var(--primary-dark);
}
.read-more-link i {
    margin-left: 5px;
    transition: transform 0.3s ease;
}
.read-more-link:hover i {
    transform: translateX(3px);
}
.view-more-btn {
    text-align: center;
    margin-top: 50px;
}


/* ========================================= */
/* 联系我们 Section */
/* ========================================= */
.contact-section {
    background-color: white;
    padding: 80px 0 50px;
}
.contact-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    gap: 30px;
    margin-top: 40px;
    margin-bottom: 50px;
}
.contact-item {
    text-align: center;
    padding: 30px;
    background-color: var(--bg-color-light);
    border-radius: 10px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.08);
    border-bottom: 4px solid var(--primary-color);
}
.contact-item i {
    font-size: 3em;
    color: var(--primary-color);
    margin-bottom: 20px;
}
.contact-item h3 {
    font-size: 1.5em;
    color: var(--primary-dark);
    margin-top: 0;
    margin-bottom: 10px;
}
.contact-item p {
    font-size: 0.95em;
    color: #666;
    margin: 0;
}
.contact-item a {
    color: var(--primary-color);
    text-decoration: none;
}
.contact-item img {
    width: 100px;
    height: 100px;
    margin-top: 15px;
    border-radius: 5px;
    box-shadow: 0 2px 5px rgba(0,0,0,0.1);
}


/* ========================================= */
/* 底部 Footer */
/* ========================================= */
.main-footer {
    background-color: var(--bg-color-dark);
    color: var(--light-text-color);
    padding: 50px 0 30px;
    font-size: 0.95em;
}
.footer-columns {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
    gap: 30px;
    margin-bottom: 40px;
}
.footer-col h4 {
    font-size: 1.3em;
    margin-bottom: 20px;
    color: var(--primary-color);
    position: relative;
    padding-bottom: 10px;
}
.footer-col h4::after {
    content: '';
    position: absolute;
    left: 0;
    bottom: 0;
    width: 40px;
    height: 3px;
    background-color: var(--primary-color);
    border-radius: 2px;
}
.footer-col ul {
    list-style: none;
    padding: 0;
    margin: 0;
}
.footer-col ul li {
    margin-bottom: 10px;
}
.footer-col ul li a {
    color: rgba(255,255,255,0.7);
    text-decoration: none;
    transition: color 0.3s ease;
}
.footer-col ul li a:hover {
    color: var(--primary-color);
}
.social-icons {
    margin-top: 20px;
}
.social-icons a {
    color: var(--light-text-color);
    font-size: 1.8em;
    margin-right: 15px;
    transition: color 0.3s ease, transform 0.2s ease;
}
.social-icons a:hover {
    color: var(--primary-color);
    transform: translateY(-3px);
}
.footer-bottom {
    text-align: center;
    padding-top: 30px;
    border-top: 1px solid rgba(255,255,255,0.1);
    color: rgba(255,255,255,0.6);
}
.footer-bottom a {
    color: rgba(255,255,255,0.7);
    text-decoration: none;
    margin: 0 8px;
    transition: color 0.3s ease;
}
.footer-bottom a:hover {
    color: var(--primary-color);
}

/* ========================================= */
/* Page Specific Styles (About Us) */
/* ========================================= */
.page-hero-section {
    background-size: cover;
    background-position: center;
    color: white;
    text-align: center;
    padding: 100px 20px;
    position: relative;
    overflow: hidden; /* 防止背景图溢出 */
    box-shadow: inset 0 -5px 15px rgba(0,0,0,0.2);
}
.page-hero-section::before { /* 叠加一层半透明背景 */
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0,0,0,0.4);
    z-index: 1;
}
.page-hero-section .container {
    position: relative;
    z-index: 2;
    text-shadow: 0 2px 8px rgba(0,0,0,0.5);
}
.page-hero-section h1 {
    font-size: 4em;
    margin-bottom: 10px;
    letter-spacing: 2px;
}
.page-hero-section p {
    font-size: 1.5em;
    max-width: 800px;
    margin: 0 auto;
}
/* 具体的页面背景图 */
.about-hero {
    background-image: url('../images/about_banner.jpg'); /* 更新路径 */
}
.activities-hero {
    background-image: url('../images/activities_banner.jpg'); /* 更新路径 */
}

.main-content-area {
    padding-top: 50px;
    padding-bottom: 50px;
}
.content-block {
    background-color: white;
    padding: 40px;
    border-radius: 10px;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    margin-bottom: 40px;
}
.intro-flex {
    display: flex;
    align-items: center;
    gap: 40px;
    flex-wrap: wrap; /* 允许换行 */
}
.intro-text {
    flex: 2;
    min-width: 300px;
}
.intro-image {
    flex: 1;
    min-width: 280px;
    text-align: center;
}
.intro-image img {
    max-width: 100%;
    height: auto;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}

.mission-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 30px;
    margin-top: 30px;
}
.mission-item {
    background-color: var(--primary-light);
    padding: 30px;
    border-radius: 10px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    text-align: center;
}
.mission-item i {
    font-size: 3em;
    color: var(--primary-dark);
    margin-bottom: 15px;
}
.mission-item h3 {
    font-size: 1.6em;
    color: var(--primary-color);
    margin-top: 0;
}
.mission-item p {
    color: #555;
}

.organizational-chart-placeholder img {
    max-width: 100%;
    height: auto;
    margin: 30px auto;
    display: block;
    border-radius: 8px;
    box-shadow: 0 5px 15px rgba(0,0,0,0.1);
}
.department-list ul {
    list-style: none; /* 移除默认点 */
    padding: 0;
}
.department-list ul li {
    background-color: var(--bg-color-light);
    border-left: 5px solid var(--primary-color);
    padding: 15px 20px;
    margin-bottom: 10px;
    border-radius: 5px;
    box-shadow: 0 1px 5px rgba(0,0,0,0.05);
}
.department-list ul li strong {
    color: var(--primary-dark);
    font-size: 1.1em;
}

/* 时间线 */
.timeline {
    position: relative;
    padding: 20px 0;
    margin: 40px 0;
}
.timeline::before {
    content: '';
    position: absolute;
    left: 50%;
    width: 4px;
    height: 100%;
    background-color: var(--border-color);
    transform: translateX(-50%);
}
.timeline-item {
    display: flex;
    align-items: center;
    margin-bottom: 40px;
}
.timeline-item:nth-child(odd) {
    flex-direction: row-reverse; /* 奇数项在右边 */
}
.timeline-item:nth-child(even) {
    flex-direction: row; /* 偶数项在左边 */
}
.timeline-dot {
    width: 20px;
    height: 20px;
    background-color: var(--primary-color);
    border-radius: 50%;
    flex-shrink: 0;
    margin: 0 30px;
    z-index: 1;
    border: 3px solid white;
    box-shadow: 0 0 0 3px var(--primary-color);
}
.timeline-date {
    flex-shrink: 0;
    font-weight: bold;
    font-size: 1.1em;
    color: var(--primary-dark);
    width: 100px;
    text-align: right;
}
.timeline-item:nth-child(odd) .timeline-date {
    text-align: left;
}
.timeline-content {
    background-color: var(--bg-color-light);
    padding: 25px;
    border-radius: 8px;
    box-shadow: 0 2px 8px rgba(0,0,0,0.1);
    flex-grow: 1;
}
.timeline-content h4 {
    font-size: 1.3em;
    color: var(--primary-dark);
    margin-top: 0;
}
.timeline-content p {
    font-size: 0.95em;
    color: #666;
}

/* 手风琴 / 折叠面板 */
.accordion {
    margin-top: 30px;
}
.accordion-item {
    border: 1px solid var(--border-color);
    border-radius: 8px;
    margin-bottom: 15px;
    overflow: hidden;
    box-shadow: 0 2px 8px rgba(0,0,0,0.05);
}
.accordion-header {
    background-color: var(--primary-color);
    color: white;
    padding: 18px 25px;
    width: 100%;
    text-align: left;
    border: none;
    font-size: 1.15em;
    font-weight: bold;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    transition: background-color 0.3s ease;
}
.accordion-header:hover {
    background-color: var(--primary-dark);
}
.accordion-header i {
    font-size: 0.8em;
    transition: transform 0.3s ease;
}
.accordion-header.active i {
    transform: rotate(180deg);
}
.accordion-content {
    padding: 20px 25px;
    background-color: white;
    border-top: 1px solid var(--border-color);
    display: none; /* 默认隐藏 */
    overflow: hidden;
    transition: max-height 0.3s ease-out, padding 0.3s ease-out; /* 平滑展开/收起 */
    max-height: 0; /* 初始为0 */
}
.accordion-content p {
    margin: 0;
    color: #555;
}


/* ========================================= */
/* Page Specific Styles (Activities) */
/* ========================================= */
.activity-filter-section {
    text-align: center;
}
.filter-buttons {
    margin-bottom: 30px;
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
    gap: 10px;
}
.filter-btn {
    background-color: var(--bg-color-light);
    border: 1px solid var(--border-color);
    color: var(--text-color);
    padding: 10px 25px;
    border-radius: 25px;
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s, color 0.3s, border-color 0.3s;
    white-space: nowrap; /* 防止按钮文字换行 */
}
.filter-btn.active,
.filter-btn:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}
.search-bar {
    display: flex;
    justify-content: center;
    margin-bottom: 30px;
}
.search-bar input[type="text"] {
    width: 100%;
    max-width: 400px;
    padding: 12px 20px;
    border: 1px solid var(--border-color);
    border-radius: 25px;
    font-size: 1em;
    outline: none;
    transition: border-color 0.3s ease, box-shadow 0.3s ease;
}
.search-bar input[type="text"]:focus {
    border-color: var(--primary-color);
    box-shadow: 0 0 0 3px rgba(0, 86, 179, 0.2); /* 焦点蓝色光晕 */
}
.search-bar button {
    background-color: var(--primary-color);
    color: white;
    border: none;
    padding: 12px 25px;
    border-radius: 25px;
    margin-left: -50px; /* 覆盖输入框右侧边缘 */
    cursor: pointer;
    font-size: 1em;
    transition: background-color 0.3s ease;
}
.search-bar button:hover {
    background-color: var(--primary-dark);
}

.activity-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(350px, 1fr));
    gap: 30px;
}
.activity-card {
    background-color: white;
    border-radius: 10px;
    overflow: hidden;
    box-shadow: 0 5px 20px rgba(0,0,0,0.08);
    transition: transform 0.3s ease, box-shadow 0.3s ease;
}
.activity-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 10px 30px rgba(0,0,0,0.15);
}
.activity-image {
    width: 100%;
    height: 220px;
    background-size: cover;
    background-position: center;
    transition: transform 0.5s ease;
}
.activity-card:hover .activity-image {
    transform: scale(1.05);
}
.activity-content {
    padding: 25px;
}
.activity-title {
    font-size: 1.6em;
    margin-top: 0;
    margin-bottom: 10px;
}
.activity-title a {
    color: var(--primary-dark);
    text-decoration: none;
    transition: color 0.3s ease;
}
.activity-title a:hover {
    color: var(--primary-color);
}
.activity-meta {
    font-size: 0.9em;
    color: #777;
    margin-bottom: 15px;
}
.activity-meta i {
    margin-right: 5px;
    color: var(--accent-color);
}
.activity-description {
    font-size: 0.95em;
    color: #555;
    margin-bottom: 20px;
}
.activity-tags {
    margin-bottom: 15px;
}
.tag {
    display: inline-block;
    background-color: var(--primary-light);
    color: var(--primary-color);
    padding: 5px 12px;
    border-radius: 15px;
    font-size: 0.8em;
    margin-right: 8px;
    margin-bottom: 8px;
    font-weight: bold;
}
.tag-upcoming { background-color: #d4edda; color: #28a745; }
.tag-past { background-color: #f8d7da; color: #dc3545; }
.tag-online { background-color: #cce5ff; color: #007bff; }
.tag-offline { background-color: #fff3cd; color: #ffc107; }
.tag-tech { background-color: #e2e6ea; color: #6c757d; }
.tag-workshop { background-color: #d1ecf1; color: #17a2b8; }
.tag-competition { background-color: #e0f7fa; color: #00bcd4; }
.tag-course { background-color: #e6e6fa; color: #6a5acd; }
.tag-exhibition { background-color: #fce4ec; color: #e91e63; }


.pagination {
    text-align: center;
    margin-top: 50px;
}
.pagination a {
    display: inline-block;
    padding: 10px 15px;
    margin: 0 5px;
    border: 1px solid var(--border-color);
    border-radius: 5px;
    text-decoration: none;
    color: var(--primary-color);
    transition: background-color 0.3s, color 0.3s, border-color 0.3s;
}
.pagination a.active,
.pagination a:hover {
    background-color: var(--primary-color);
    color: white;
    border-color: var(--primary-color);
}


/* ========================================= */
/* 响应式设计 - Media Queries */
/* ========================================= */
@media (max-width: 1200px) {
    .main-header .container {
        padding: 0 15px;
    }
    .main-nav ul li {
        margin-left: 25px;
    }
    .carousel-caption h2 {
        font-size: 3.2em;
    }
    .carousel-caption p {
        font-size: 1.3em;
    }
    .section-heading {
        font-size: 2.5em;
    }
    .sub-heading {
        font-size: 1.8em;
    }
}

@media (max-width: 992px) {
    .main-nav {
        display: none; /* 桌面导航在小屏幕隐藏 */
    }
    .toggle-menu-btn {
        display: block; /* 移动端菜单按钮显示 */
    }
    .header-right {
        margin-left: auto; /* 搜索和菜单按钮靠右 */
    }
    .search-btn {
        margin-left: 0;
    }

    .carousel-container {
        height: 500px;
    }
    .carousel-caption h2 {
        font-size: 2.5em;
    }
    .carousel-caption p {
        font-size: 1.1em;
    }
    .nav-arrow {
        padding: 10px 15px;
        font-size: 1.5em;
    }

    .section-padded {
        padding: 60px 0;
    }
    .section-heading {
        font-size: 2.2em;
    }
    .value-grid, .stats-counter-section {
        grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
        gap: 20px;
    }
    .parallax-section {
        min-height: 350px;
    }
    .parallax-content h2 {
        font-size: 2.5em;
    }
    .parallax-content p {
        font-size: 1.1em;
    }
    .news-grid {
        grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
    }
    .contact-grid {
        grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
    }
    .footer-columns {
        grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
    }
    .page-hero-section {
        padding: 80px 20px;
    }
    .page-hero-section h1 {
        font-size: 3em;
    }
    .page-hero-section p {
        font-size: 1.2em;
    }
    .intro-flex {
        flex-direction: column; /* 垂直堆叠 */
    }
    .timeline::before { /* 时间线居中 */
        left: 20px;
        transform: translateX(0);
    }
    .timeline-item {
        flex-direction: row !important; /* 统一方向 */
        margin-left: 20px;
    }
    .timeline-dot {
        margin: 0 20px 0 0;
    }
    .timeline-date {
        text-align: left !important;
        width: auto;
        padding-right: 15px;
    }
    .accordion-header {
        font-size: 1.05em;
        padding: 15px 20px;
    }
    .activity-grid {
        grid-template-columns: 1fr; /* 单列显示 */
    }
    .search-bar input[type="text"] {
        max-width: none;
    }
    .search-bar button {
        margin-left: 10px; /* 调整搜索按钮位置 */
    }
}

@media (max-width: 768px) {
    .logo {
        font-size: 1.4em;
    }
    .logo img {
        height: 35px;
    }
    .carousel-container {
        height: 400px;
    }
    .carousel-caption h2 {
        font-size: 2em;
    }
    .carousel-caption p {
        font-size: 1em;
        margin-bottom: 20px;
    }
    .section-padded {
        padding: 40px 0;
    }
    .section-heading {
        font-size: 1.8em;
        margin-bottom: 1em;
    }
    .sub-heading {
        font-size: 1.5em;
    }
    .value-item i {
        font-size: 2.8em;
    }
    .value-item h3 {
        font-size: 1.4em;
    }
    .stats-counter-section {
        padding: 30px;
    }
    .stat-item .counter {
        font-size: 2.8em;
    }
    .stat-item p {
        font-size: 1.1em;
    }
    .parallax-section {
        min-height: 300px;
    }
    .parallax-content h2 {
        font-size: 2em;
    }
    .parallax-content p {
        font-size: 1em;
    }
    .news-content {
        padding: 18px;
    }
    .news-content h4 {
        font-size: 1.2em;
    }
    .btn {
        padding: 10px 20px;
        font-size: 1em;
    }
    .page-hero-section h1 {
        font-size: 2.5em;
    }
    .page-hero-section p {
        font-size: 1.1em;
    }
    .content-block {
        padding: 30px;
    }
    .timeline-item {
        margin-bottom: 30px;
    }
    .timeline-content {
        padding: 18px;
    }
    .filter-btn {
        padding: 8px 18px;
        font-size: 0.9em;
    }
    .search-bar input[type="text"] {
        padding: 10px 15px;
        font-size: 0.9em;
    }
    .search-bar button {
        padding: 10px 20px;
        font-size: 0.9em;
    }
    .activity-card .activity-image {
        height: 180px;
    }
    .activity-title {
        font-size: 1.4em;
    }
}

@keyframes fadeInSlideUp {
    from {
        opacity: 0;
        transform: translateY(20px);
    }
    to {
        opacity: 1;
        transform: translateY(0);
    }
}